Earth has a rigid outer layer, known as the lithosphere. The lithosphere is broken into continental and regional sized tectonic plates and these plates move in conjunction with each other. These plates also interact along their plate boundaries, where they converge, diverge and slide past one another (Wilson, J, Lam, N & Pham, L 2008). Such interactions are responsible for the majority of Earth’s seismic activity. As these tectonic plates slide past one another, their rough patches of rock interlock. Despite the fault boundaries being locked together, the tectonic plates continue to grind against one another, pulling at the interlocked sections. This pulling begins to strain the two tectonic plates and builds up pressure (Wilson, J, Lam, N & Pham, L 2008).
Once the accumulated pressure exceeds the strength of the two rock masses, the two tectonic plates of the fault slide past one another, releasing the built-up pressure, rupturing the Earth’s crust and creating more faults near the boundaries of the two plates. Violent energy and seismic waves from this separation radiate outward in all directions, including the surface of the lithosphere and local zones of weakness, where it is felt as an earthquake (Wilson, J, Lam, N & Pham, L 2008). .
EARTHQUAKE ACTIVITY IN SOUTH AUSTRALIA 